Make a tacky-but-homey enchilada casserole: Preheat the oven to 400°F (205°C). Shred leftover drained chicken (reserve 1 cup/240 ml of the stew liquid) and add cooked and drained black beans to make 1½ cups (360 ml). Heat 9 corn tortillas on a hot griddle or in a skillet or sauté pan over medium-high heat until pliable. Lightly oil a 7 by 11-inch (17.5 by 28-cm) baking dish and layer the tortillas (cut to fit as necessary) and chicken and beans in the baking dish. Combine the reserved stew liquid and 1 cup (240 ml) crushed tomatoes, season with salt to taste, and pour over the casserole. Cover with as much shredded Monterey Jack or cheddar cheese as you feel is appropriate and bake until bubbly, about 30 minutes. Let settle for a few minutes before scooping out servings.